Cytologic findings of clear cell hidradenoma in the male breast skin

A case report

Abstract

Background: Clear cell hidradenoma is a relatively rare skin appendage tumor, the cytologic findings of which have not been well documented.
Case: A 60-year-old male had noticed a gradually enlarging mass in his right breast for 2 years. Fine needle aspiration biopsy cytology revealed moderately cellular smears composed of tumor cells showing distinctive two types and/or patterns ; 1) clusters of squamoid cells with a sheet-like arrangement, possessing a polyhedral cytoplasm that stained faintly with light-green and centrally located oval nuclei, 2) discohesive or individual clear cells with irregularly shaped hyperchromatic naked nuclei, and discohesive squamoid cells also showing naked nuclei. The former clusters also contained scattered small cells with dark-stained nuclei resembling myoepithelial cells. No bipolar naked nuclei were seen. The cytologic diagnosis was Class II, a benign tumor derived from skin appendage or mammary gland. Histological examinations of the submitted material revealed a clear cell hidradenoma (3.5 cm in size) in the dermis supporting our cytological diagnosis.
Conclusion: We should take into consideration the possibility of skin appendage tumor in the differential diagnosis when the cytologic specimen has been aspirated from subcutaneous or soft tissue.